I would like to start off by saying i know that this would not be an immediate solution, but something of a long term project that would solve the issue that makes adventures impossible to convert to tall tales. Its a high effort idea, but i think it would help the games development in the long run.
It was made clear that the main reason why adventures are temporary is because once something is made a part of a tall tale, that thing is cemented into the world permanently. But perhaps instead any area that was made a part of a tall tale could be disconnected from the main map and instead different modules were made for each use needed!
This would work by having a main module that is used by default as a regular part of the map if no adventure/tall tale was active, then if a tall tale, or even possible future quest was activated, as some one got near the objective it could switch out modules to what is needed. For a rough example, the default module for vaults could hold gold with little trouble, and as is work with the existing tall tales just fine, but in the future if they wanted to add a destroyed vault that is damaged, or an expanded version for a tall tale, it would swap modules.
This entire idea came to me when realizing that the system is already partly implemented with the veil of the ancients final segment, where a whole set of structures is placed into the world, which is already half of the work, but even on said structures, when they take enough damage, one module is removed and replaced with a destroyed module! I do understand that the veil forts are a bit different however since they spawn in the middle of the sea where nothing else is, but it does show the mechanic is partly in play already.
It may be a lot of effort to pull off, but i do believe that it would be a solution that would make it possible to go back to older adventures as tall tales for those who have missed them, and those who wish to do them again.
